Browsing by Author "Wang, W"

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A watt-level 2.3-GHz GaAs MESFET power amplifier with gap-coupled microstrip-line matching topology
(2004-06-05)
Meng, CC
;
Wang, W
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電信工程研究所
;
Institute of Communications Engineering
A one-stage hybrid power amplifier integrated with gap-coupled microstrip lines for impedance matching is demonstrated in this work. The gap-coupled microstrip line amplifier module realized here can provide IS-dB power gain, 33.5-dBm output power, and 42% power-added efficiency (PAE) at 2.3 GHZ. The demonstrated topology is suitable in monolithic 1C technology, especially in the millimeter-wave frequency because the gap-coupled microstrip lines can he easily compacted into small size. 2004 Wiley Periodicals, Inc.
High-linear-power MESFET devices using source-degeneration inductance and input-impedance mismatch
(2006-05-01)
Meng, CC
;
Wang, W
;
電信工程研究所
;
Institute of Communications Engineering
Linearity can be improved drastically by sacrificing power gain with the same output power. GaAs MESFET devices with via-hole ground and with bond-wire ground are used to investigate the effect of source-inductive feedback and input-impedance mismatch on the effect of linearm. At 2.4 GHz the device without bond-wire ground and mismatched input impedance has the highest linearity OIP3 = 50 dBm, gain = 13.5 dB gain, and P-tdB = 29 dBm, while the device with via-hole ground and inatched input impedance has the lowest linearity OIP3 = 40 dBm, 18.3 dB gain, and P-tdB = 29 dBm. (c) 2006 Wiley Periodicals, Inc.
Learning portfolio analysis and mining for SCORM compliant environment
(2006)
Su, JM
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Tseng, SS
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Wang, W
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Weng, JF
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Yang, JTD
With vigorous development of the Internet, e-learning system has become more and more popular. Sharable Content Object Reference Model (SCORM) 2004 provides the Sequencing and Navigation (SN) Specification to define the course sequencing behavior, control the sequencing, selecting and delivering of course, and organize the content into a hierarchical structure, namely Activity Tree. Therefore, how to provide customized course according to individual learning characteristics and capabilities, and how to create, represent and maintain the activity tree with appropriate associated sequencing definition for different learners become two important issues. However, it is almost impossible to design personalized learning activities trees for each learner manually. The information of learning behavior, called learning portfolio, can help teacher understand the reason why a learner got high or low grade. Thus, in this paper, we propose a Learning Portfolio Mining (LPM) Approach including four phases: 1. User Model Definition Phase: define the learner profile based upon existing articles and pedagogical theory. 2. Learning Pattern Extraction Phase: apply sequential pattern mining technique to extract the maximal frequent learning patterns from the learning sequence, transform original learning sequence into a bit vector, and then use distance based clustering approach to group learners with good learning performance into several clusters. 3. Decision Tree Construction Phase: use two third of the learner profiles with corresponding cluster labels as training data to create a decision tree, and the remainings are the testing data. 4. Activity Tree Generation Phase: use each created cluster including several learning patterns as sequencing rules to generate personalized activity tree with associated sequencing rules of SN. Finally, for evaluating our proposed approach of learning portfolio analysis, an experiment has been done and the results show that generated personalized activity trees with sequencing rules are workable and beneficial for learners.
Linearity improvement for power MESFET devices using source inductive feedback and input impedance mismatch
(2005)
Meng, CC
;
Wang, W
;
電信工程研究所
;
Institute of Communications Engineering
Linearity can be improved drastically by sacrificing power gain with the same output power. GaAs MESFET devices with source-via-hole ground and with source-bond-wire ground are used to investigate the effect of source inductive feedback and input impedance mismatch on the effect of linearity. The output matching for all the devices are tuned for the maximum power condition. At 2.4 GHz, the device without source-bond-wire ground and input impedance mismatched has the highest linearity, OIP3=50 dBm, gain=13.5 dB gain and P-1dB=29 dBm while the device with source-via-hole ground and input impedance matched has the lowest linearity OIP3=40 dBm, 18.3 dB gain and P-IdB=29 dBm.